Canine ocular tumors following ciliary body ablation with intravitreal gentamicin

Abstract

Iridociliary tumors are the second most common primary ocular tumor in dogs and are usually benign. A review of the Comparative Ocular Pathology Laboratory of Wisconsin (COPLOW) database in 2009 suggested a potential correlation between malignant iridociliary epithelial tumors and ciliary body ablation by intravitreal gentamicin injection for the treatment of glaucoma. The purpose of this case series was to determine whether there is evidence of such a correlation in the COPLOW collection. Mining of the COPLOW database revealed that a significant number (39.5%) of canine globes with a history of ciliary body ablation were subsequently diagnosed with primary ocular tumors at enucleation, most commonly iridociliary epithelial tumors and melanocytic tumors. It is possible that neoplasia was present but unrecognized at the time of ciliary body ablation. These tumors had a higher than expected incidence of malignancy. These cases underscore the importance of reserving ciliary body ablation with gentamicin for disease-free eyes.

Measurement of plasma gentamicin concentrations postchemical ciliary body ablation in dogs with chronic glaucoma

“…Reported complications of ciliary body ablation with intravitreal gentamicin in dogs include intraocular inflammation, corneal opacity, cataract formation, intraocular hemorrhage, and phthisis bulbi . A recent report suggests that there may be a possible correlation between intravitreal injection of gentamicin in dogs and the augmentation of preexisting intraocular neoplasia . In that report, the tumors in eyes that had a previous intravitreal injection of gentamicin had a higher than expected incidence of malignancy, but it is also possible that the neoplasia was present at the time of the chemical ablation.…”

Feline ocular tumors following ciliary body ablation with intravitreal gentamicin

“…Although there is a suggested link between trauma and intraocular melanoma development in humans, there is no evidence of such a relationship in the veterinary literature . However, there is a suggested correlation between gentamicin and tumor promotion/malignancy in canines . In the present cases, it is more likely that occult neoplasm was present in the eye before the gentamicin was administered; such tumors are feasibly the cause of secondary glaucoma that necessitated intervention.…”

“…[11][12][13] However, there is a suggested correlation between gentamicin and tumor promotion/malignancy in canines. 14 the present cases, it is more likely that occult neoplasm was present in the eye before the gentamicin was administered; such tumors are feasibly the cause of secondary glaucoma that necessitated intervention. In contrast, there is a very real possibility that ciliary body ablation is the trauma that caused post-traumatic sarcomas in these three cats.…”

Surgical Treatment of Canine Glaucoma

“…27,88,89 Although the measurable levels of gentamicin present in the blood of treated animals are unlikely to be nephrotoxic or ototoxic in healthy dogs, caution has been recommended when administering intravitreal gentamicin in small patients. 85 Recently, a study has identified the presence of intraocular tumors in 40% of enucleated eyes that had been previously treated with intravitreal gentamicin injection (IGI) 90 ; although the study could not prove a causal correlation between the injection of gentamicin and the development of tumors, it is concerning that a large portion of those tumors exhibited unusual malignant behavior. Thorough ocular examination, including ocular ultrasonography, should always be performed before proceeding for IGI in dogs.…”